There is a cosy consensus in the UK that our state broadcaster (funded by a regressive tax on all television owners) is utterly, unimpeachibly, unbiased.
This is, of course, nonsense but it's often hard to prove.
The guys at Biased BBC do a good job of highlighting the "stealth edits" of BBC News online articles, the degree to which interviewers on "Today" give interviewees a hard time and much more.
However, a potentially even more interesting new service has just started up: "News Sniffer" does a couple of things but one of the most important is spotting all the times that the BBC edit an article on their website without changing the "last updated" timestamp.
From a quick glance, most of the edits are minor corrections and clarifications but the service will come into its own when a contentious issue is in the news.